The present application is directed to an antimicrobial composition for protecting wood. More specifically, the present application is directed to a multifunctional broad spectrum antimicrobial composition which can be incorporated into a wood preservative, or can be used as an antimicrobial additive in water-based wood and wood composite coatings.
Wood surfaces, such as those on buildings and other structures which are exposed to the environment, are susceptible to attack by microbes such as fungi or bacteria and other pests. For example, in areas such as the Lower Mainland of British Columbia, mold growth on attic roof components, especially on wood framing and sheathing, can occur because of roof leaks or water vapor condensation. When air-borne fungal spores and/or tiny air-borne mycelia fragments land on wet or damp wood surfaces, initial mold culture can become established and later proliferate into large colonies. Attempts to prevent the significant condensation problem in such areas by re-designing roofs have not so far successfully addressed the issue.
Fungal attack of wood surfaces can compromise or destroy the structural integrity of the wood, as well as damage its appearance. As well, mold colonies can release high levels of mycotoxins to prevent invasion by competitive organisms. As a result, apart from cosmetic problems, mold growth can cause adverse health effects in humans, and considerably reduce the commercial value of structures.
Coatings and preservatives for such wood surfaces therefore often include antimicrobial compounds to protect the wood from damage caused by such microbes. A wide variety of antimicrobial compounds are known to be used in such wood preservatives and coatings. However, in many cases, such antimicrobial compounds are less effective against some species than others, and may need to be present at relatively high levels to have broad spectrum effectiveness against an adequate range of microbes. Alternatively, combinations of individual antimicrobial products, each of which individually has effectiveness against a specific species or groups of species, may be necessary to achieve broad spectrum effectiveness against the desired range of microbes.
For some applications of wood coatings, it is desirable that such antimicrobial compounds be present at low levels or absent. Many such antimicrobial compounds can be harmful to humans or animals. Thus, if it is likely that humans or animals will come into contact with a coated wood surface, it is desirable to prevent or minimize exposure to potentially harmful levels of antimicrobial compounds caused by such contact. Furthermore, in some cases, wood surfaces may not be exposed to an environment where attack by microbes is a substantial risk, and therefore would not need a high level of antimicrobial protection. In such cases, there would be no need to risk exposing users to high levels of antimicrobial compounds during application of a coating. Thus, manufacturers who wish to provide a choice of coatings to their customers must develop a number of different antimicrobial or non-antimicrobial formulations at additional effort and cost.
Therefore, there is a need for an antimicrobial composition which can be conveniently stored and diluted as needed to provide a wood preservative, or which can be added to wood preservative and wood coating formulations so as to provide the formulations with antimicrobial properties as desired. In this way, coating manufacturers can readily achieve alternative antimicrobial protection for existing coatings without the need for costly or time-intensive research. In some cases, non-antimicrobial coatings, such as interior paints and stains, could be readily adapted for applications requiring antimicrobial properties.
In addition, it is desirable to provide an antimicrobial composition which has antimicrobial activity against a range of wood-attacking microbes, so as to reduce the need for treatment with multiple products, each containing individual antimicrobial agents.